For a sliding member, such as a piston ring for use in internal combustion engines, a technique of enhancing the abrasion resistance thereof has been made public in Japanese Patent Laid-Open Publication (JP-A) 8-296030 (1996), where the enhancement is enabled by forming an ion-plating deposition layer of CrN, also including Cr2N, on the external circumferential sliding surface thereof, by means of a physical vapor deposition (PVD) method.
There are two types in the publicly known ion-plating deposition layers composed mainly of chrome nitride including Cr2N and CrN, i.e., one type of deposition layer having the CrN of the chrome nitride which has a preferred orientation of the plane {111}, and the other type having the CrN of the chrome nitride which has a preferred orientation of the plane {100}. A deposition layer of the CrN having the preferred orientation of the plane {111}, is superior in abrasion resistance and scuffing resistance, but, due to having high internal stress, is inferior in peeling resistance, to a deposition layer of CrN having the preferred orientation of the plane {100}. On the contrary, or inversely, a deposition layer of the CrN having the preferred orientation of the plane {100}, is inferior in abrasion resistance and scuffing resistance, but, because of the porosity thereof being easily controllable, is superior in peeling resistance, to a deposition layer of the CrN having the preferred orientation of the plane {111}.
An object of the present invention therefore is to provide a sliding member having an ion-plating deposition layer, composed mainly of chrome nitride including Cr2N and CrN, that has abrasion resistance and scuffing resistance enhanced, or improved, while maintaining the excellent peeling resistance level of a deposition layer of the CrN having the preferred orientation of the plane {100}.